Open drain drivers have many applications. For example, open drain drivers are commonly used to drive a logic signal onto a shared bus. One advantage of using an open drain driver in such an application is that the open drain driver is in a high impedance state when not driving the low signal onto the shared bus, which isolates the circuitry associated with the open drain driver from the shared bus. In such cases, where multiple circuits are sharing a bus, the supply voltages of the circuits may vary. Some circuits may operate with a low power supply voltage, while other circuits operate with a high power supply voltage.